Back to EveryPatent.com
United States Patent |
5,186,882
|
Hafner
|
February 16, 1993
|
Method for mounting a filter on the valve
Abstract
A method for mounting a filter on the valve, the filter includes a filter
cloth which is disposed on the circumference of the valve body in such a
way that the filter cloth covers the through openings of the valve body.
The filter cloth is provided with a sprayed plastic coating except in the
area of the through openings in order to fix the filter cloth in its
position relative to the through openings. In this way, contamination of
the valve interior with plastic particles is avoided. The method according
to the invention is particularly suitable for fuel injection valves for
fuel injection systems of internal combustion engines.
Inventors:
|
Hafner; Udo (Ludwigsburg, DE)
|
Assignee:
|
Robert Bosch GmbH (Stuttgart, DE)
|
Appl. No.:
|
800308 |
Filed:
|
November 29, 1991 |
Foreign Application Priority Data
Current U.S. Class: |
264/257; 156/272.8; 239/533.2; 239/584; 239/900; 264/274 |
Intern'l Class: |
B01D 035/02; F02M 051/08; B29C 067/18 |
Field of Search: |
264/257,274
156/272.8
239/900,584,533.2
|
References Cited
U.S. Patent Documents
1949106 | Feb., 1934 | Manneschmidt | 137/549.
|
2005445 | Jun., 1935 | Wiedhoff | 137/549.
|
3371138 | Feb., 1968 | Zablocki | 264/309.
|
3440086 | Apr., 1969 | Kerns | 264/309.
|
3839533 | Oct., 1974 | Laing | 264/309.
|
4311168 | Jan., 1982 | Peters et al. | 137/549.
|
4416238 | Nov., 1983 | Knapp et al. | 239/533.
|
4646975 | Mar., 1987 | Horn | 239/584.
|
4771948 | Sep., 1988 | Furukawa et al. | 239/900.
|
5088518 | Feb., 1992 | Stamatakis et al. | 137/549.
|
5088650 | Feb., 1992 | Takagi et al. | 239/584.
|
Foreign Patent Documents |
3841010 | Jun., 1990 | DE.
| |
2044429 | Feb., 1987 | JP | 156/272.
|
1-310934 | Dec., 1989 | JP | 156/272.
|
2225810 | Jun., 1990 | GB.
| |
Primary Examiner: Hoag; Willard
Attorney, Agent or Firm: Greigg; Edwin E., Greigg; Ronald E.
Claims
What is claimed and desired to be secured by Letters Patent of the United
States is:
1. A method for mounting a filter on the circumference of a valve body of a
valve, especially of a fuel injection valve, said valve body defining in a
radial direction the outside of the valve, the valve body having at least
one through opening on its circumference, through which fuel flows, the
method steps comprise applying a filter cloth in such a way on the
circumference of the valve body that the at least one through opening is
covered by the filter cloth, spraying a plastic coating onto different
portions of the filter cloth, leaving at least one opening through which
fuel can flow through the filter cloth and the at least one through
opening into the valve body and permitting the plastic coating to cool
thereby shrinking on the filter cloth, and on at least one portion of the
circumference of the valve body so as in this way to fix the filter cloth
in its position relative to the valve body.
2. A method as defined by claim 1, wherein the valve body has at least one
recess on its circumference, and filling the recess with the sprayed
plastic coating during spraying of the plastic coating.
3. A method as defined by claim 1, in which the valve body has on its
circumference at least one flattened surface portion which is closely
surrounded by the sprayed plastic coating of the filter.
4. A method as defined by claim 2, in which the valve body has on its
circumference at least one flattened surface portion which is closely
surrounded by the sprayed plastic coating of the filter (1).
5. A method as defined by claim 1, in which the valve body is a nozzle body
of the valve.
6. A method as defined by claim 1, in which the valve body is a valve
housing of the valve.
Description
BACKGROUND OF THE INVENTION
The invention is based on a valve and a method for mounting a filter on the
circumference of the valve body which defines a valve radially outwardly,
and a valve, as defined hereinafter. In a valve known for instance from
German Offenlegungsschrift 38 41 010 A1, a filter element is slipped onto
the valve housing so that the at least one continuous opening embodied on
the circumference of the valve housing is covered by the filter cloth in
the region of the flow openings of the filter element. The filter element
is produced by coating a filter cloth with plastic in an injection tool.
When the filter element is mounted on the valve body, there is the danger
that burrs on the filter element, which are created when it is removed
from the molding tool, can become detached and contaminate the interior of
the valve. Moreover, solely from the joining process, there is the
possibility of removal of material from the inside of the filter element,
since to fix its position it is necessary to press the filter on the valve
housing.
Graduations of the diameter with round edges are also necessary on the
valve body, to enable the filter element to be slipped onto the valve
body, for instance onto the valve housing of the valve. Forming these
graduations increases the production cost for a valve made in this way.
OBJECT AND SUMMARY OF THE INVENTION
The method according to the invention for mounting a filter on the
circumference of a valve body, defining a valve radially outward has an
advantage over the prior art that contamination of the valve interior is
avoided, since the filter is not slipped onto the valve body and so no
particles of material can be scraped off. The tightness between the
sprayed plastic coating serving as a cloth holder and the valve body is
attained by shrinking the sprayed plastic coating onto the valve body
immediately after the coating process, as a result of the cooling of the
plastic material. A further advantage is simpler and more economical
production of the valve, because no diameter graduations with rounded
edges are required on the circumference of the valve body in order to
mount the filter.
It is particularly advantageous if the valve body has at least one recess
on its circumference that is filled with the sprayed plastic coating. This
assures a secure, reliable hold of the filter on the circumference of the
valve body. It is also advantageous if the valve body has at least one
flattened surface portion on its circumference, which is surrounded
closely by the sprayed plastic coating of the filter. This effectively
prevents twisting of the filter on the circumference of the valve body.
The invention will be better understood and further objects and advantages
thereof will become more apparent from the ensuing detailed description of
preferred embodiments taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a first exemplary embodiment of a valve with a filter mounted
thereon in accordance with the invention;
FIG. 2 is a fragmentary section of the first exemplary embodiment shown in
FIG. 1; and
FIGS. 3 and 4, respectively, show a second and third exemplary embodiment
of a valve with a filter mounted thereon according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The valves shown in FIGS. 1 to 4, in the form of electromagnetically
actuatable fuel injection valves for fuel injection systems, for instance
of mixture-compressing internal combustion engines with externally
supplied ignition, have a filter 1 mounted in accordance with the
invention, which serves to filter a fluid delivered to the valve. Elements
that are the same and function the same are identified by the same
reference numerals in all four drawing figures.
In the first exemplary embodiment shown in FIGS. 1 and 2, the filter I is
disposed on the circumference of a tubular nozzle body 5 that defines the
valve radially outward. The nozzle body 5 has at least one and for
instance two through openings 7 on its circumference, in the form of slits
partly encompassing it, all of which are located at approximately the same
axial height along the nozzle body 5.
These through openings 7 serve to deliver a fuel, for instance, into the
interior of the tubular nozzle body 5. To actuate the valve, the valve has
an electrical connection plug 11 on one end, which serves to provide
electrical contact with a magnetic coil, not shown. On its end remote from
the connection plug 11, a valve seat body 13 is slipped into a
longitudinal opening 14 of the nozzle body 5 that extends concentrically
with a longitudinal axis 9 of the valve. The valve seat body 13 is joined
on its circumference to the wall of the longitudinal opening 14, on the
end thereof remote from the electrical connection plug 11, for instance by
means of a laser-welded seam 16.
In the upstream direction, toward the through openings 7 of the nozzle body
5, the valve seat body 13 has a guide bore 15 extending concentrically
with the longitudinal valve axis 9, and a ball 17 that serves as a valve
closing body is slidable supported in the guide bore 15. A fixed valve
seat 19 that cooperates with the ball 17 is embodied in the valve seat
body 13 downstream of the guide bore 15. The wall of the guide bore 15 is
interrupted by fuel conduits 21 extending axially, which enable a flow of
fuel to the valve seat 19. Downstream of the valve seat 19 in the valve
seat body 13, injection ports 23, for instance two in number, are formed,
which inject the fuel into a preparation bore 25 of the valve seat body
13; the preparation bore extends concentrically with the longitudinal
valve axis 9 and widens in the downstream direction.
The ball 17 serving as the valve closing body is joined, remote from the
valve seat 19, directly to a tubular armature 27, for instance by laser
welding. The armature 27 cooperates with the magnetic coil and a core, not
shown, of the valve and serves to actuate the valve. A retaining shoulder
31 is formed in a through bore 29 of the armature 27, and on this shoulder
a restoring spring 33 is supported, oriented toward the valve seat 19 of
the valve seat body 13. The restoring spring 33 is arranged to move the
ball 17, serving as the valve closing body, in the direction of its valve
seat 19, and thus to close the valve.
To mount the filter 1 on the circumference of the nozzle body 5, in a first
method step according to the invention, a filter cloth 35 is disposed in
such a way on the circumference of the nozzle body 5 that the through
openings 7, for instance two in number, of the nozzle body 5 are covered
by the filter cloth 35. To enable simple mounting of the filter cloth 35
on the circumference of the nozzle body 5 and to assure that the filter
cloth 35 will be held on the nozzle body 5 until the filter 1 is finished,
it is practical to use an annular filter cloth 35. A filter cloth 35 of
this kind can be produced, in a known manner, for instance by welding
together the two ends of a strip-like filter cloth.
It is also possible, as in FIG. 3, which shows a second exemplary
embodiment of a valve according to the invention, to cover the through
openings 7 of the nozzle body 5 with individual pieces of filter cloth,
which are somewhat larger than the cross section of the applicable through
opening .7 which may have a round, rectangular, oval or other shape. The
pieces of filter cloth accordingly then extend only part-way over the
circumference of the nozzle body 5.
At least one recess 37 is embodied on the circumference of the nozzle body
5, for instance in the region covered by the filter cloth 35; in the first
exemplary embodiment shown, the recess has the form of an encompassing
groove. In a second method step, the nozzle body 5, in the region of the
filter cloth 35, is provided with a sprayed plastic coating 39 partly
covering the filter cloth 35; above and below the opening 7; after the
coating operation, this coating cools down and shrinks, so that the filter
cloth 35 is fixed in its position relative to the through openings 7 of
the nozzle body 5, and the sprayed plastic coating 39 sealingly encloses
the nozzle body 5. The recess 37 formed on the circumference of the nozzle
body 5 is filled with the sprayed plastic coating 39, so that a
particularly firm, secure hold of the filter 1, comprising the filter
cloth 35 and the sprayed plastic coating 39 is attained, in the axial
direction on the circumference of the nozzle body 5. To prevent twisting
of the filter 1 on the circumference of the nozzle body 5, it is also
possible, as shown in FIG. 3, for there to be at least one flattened
surface 38, which is tightly surrounded by the sprayed plastic coating 39,
embodied on the circumference of the nozzle body 5 in the region of the
sprayed plastic coating 39.
The sprayed plastic coating 39 of the filter 1 has an upper collar 40 on
its end remote from the valve seat 19 and a lower collar 42 on its end
toward the valve seat 19. With one, upper end face 44, formed by the upper
collar 40 of the plastic coating 39, the filter 1 rests on a holding face
46 of the nozzle body 5 that is oriented toward the filter 1 and points
radially outward.
Between the upper collar 40 and the lower collar 42 of the plastic coating
39, flow openings 48 are formed in the plastic coating 39 that cover the
filter cloth 3 in the region of the through openings 7 of the nozzle body
6 and thus serve to supply fuel to the valve. The flow openings 48 are
defined by axially extending ribs 50, which join the upper collar 40 and
lower collar 42 of the plastic coating 39 of the filter 1 together in
areas other than over the through openings 7, and which also support the
filter cloth 35 of the filter and hold it securely and reliably on the
circumference of the nozzle body 5 in the region of the through openings
48. That is, along the upper and lower portions of the nozzle body 5 along
the through openings 7 and at the ends of the through openings 7.
In the region of the laser-welded seam 16, extending in an encompassing
cross-sectional reduction 52 of the nozzle body 5, the nozzle body 5 is
surrounded by a retaining collar 54. The encompassing retaining collar 54
is made jointly with the embodiment of a plastic sheath 56 that partly
surrounds the valve in the axial direction. The plastic material of the
retaining collar 54 fills the encompassing cross-sectional reduction 52 of
the nozzle body 5 and thus protects the laser-welded seam 16 from external
damage in a simple manner.
A sealing ring 58 is disposed o the circumference of the nozzle body 5,
axially between the lower collar 42 of the filter 1 and the retaining
collar 54. The sealing ring 58 serves the purpose of sealing between the
circumference of the valve and a valve holder, not shown, such as an
intake line of the engine.
FIG. 4 shows a third exemplary embodiment of a valve, embodied for instance
as a fuel injection valve, having a filter 1 mounted according to the
invention. In this exemplary embodiment, the filter 1 is disposed on the
circumference of a valve housing 61 radially defining the valve toward the
outside. The valve housing has six through openings 7, for instance on its
circumference, which are in the form of bores and all of which are located
at least approximately at the same axial height and serve to deliver a
fuel, for instance, through the wall of the valve housing 61 into the
interior of the valve or serve to allow excess fuel to drain out of the
valve. Such a filter may be used on a valve housing which has both an
inflow and outflow of fuel at different portions of the valve housing.
To mount the filter 1 on the circumference of the valve housing 61, the
filter cloth 35, which for instance is in the form of a ring, is disposed
on the circumference of the valve housing 61, in a first method step
according to the invention, in such a way that the six through openings 7
are covered by the filter cloth 35. In a second method step, the valve
housing 61 is provided in the region of the filter cloth 35 with a sprayed
plastic coating 39, which partly covers the filter cloth 35 and which,
after the coating operation, cools down and shrinks, so that the filter
cloth 35 is retained in its position relative to the through openings 7 of
the valve housing 61, and the plastic coating 39 sealingly encloses the
valve housing 61.
The upper collar 40 and lower collar 42 of the plastic coating 39 of the
filter 1 serve essentially to retain the filter 1 on the circumference of
the valve housing 61. Between the upper collar 40 and the lower collar 42
in the plastic coating 39, flow openings 48 ar provided to supply fuel to
the valve; they extend across the filter cloth 35 in the region of the
through openings 7 of the valve body 5. The ribs 50, formed in the axial
direction between the upper collar 40 and lower collar 42 define the flow
openings 48 in the circumferential direction of the filter 1, support the
filter cloth 35 of the filter 1, and retain it on the circumference of the
valve housing 61.
A sealing ring 63 is disposed on the circumference of the valve housing 61.
The axial mobility of the sealing ring 63 is limited by the upper face end
44 of the upper collar 40 of the filter 1 and by a retaining flange 65 of
the plastic sheath 56 of the valve, the flange being oriented toward the
electric connection plug 11 of the valve. The method according to the
invention offers the advantage that as a result of the direct application
of the sprayed plastic coating 39 on the circumference of the valve body
5, 61 in the region of the filter cloth 35, a filter 1 is formed in a
simple manner in such a way that contamination of the valve interior is
avoided.
The foregoing relates to preferred exemplary embodiments of the invention,
it being understood that other variants and embodiments thereof are
possible within the spirit and scope of the invention, the latter being
defined by the appended claims.
Top